When a person is born again, God immediately begins a process of conforming that person to His Son, and one manifestation of that conformation is increasing government over self, a growth in holiness.
God then has a plan that Godly people living in families would exercise family government within homes and families.
Beyond the family, God has ordained civil magistrates to govern for the purpose of restraining evil among all people in their jurisdiction, heathens and pagans included.
It is a Christian responsibility to exert pressure (salt and light) on the civil government to ensure its conformance to properly defining good and evil based on God's law.